Abstract

Atomic configurations of an bulk metallic glass and its molten state have been investigated. The supercooled liquid and melt have a volume expansion coefficient only two times as large as that below glass transition temperature. Although the dominant polyhedra are 12- and 13-coordinated, the melt has slightly more polyhedra of low coordinated and less of high coordinated than in the as-cast. By Gd addition, half-octahedra with more volume accommodated are likely formed in the polyhedra, causing the local atomic environments of Mg in the melt quite different from the competing crystalline phase, thereby suppressing crystallization upon quenching.

Received 05 November 2010Accepted 27 December 2010Published online 19 January 2011

Acknowledgments:

The authors are grateful to the HASYLAB staff at Hamburg for the assistance during the measurements at BW5 and C1 stations. Financial support from the National Natural Science Foundation of China (Grant Nos. 51071141, 60776014, 60876002, 10804096, 50890174, 10702062, 50920105101, 10979002, and 51050110136), Zhejiang University-Helmholtz Cooperation Fund, and the Department of Science and Technology of Zhejiang province is gratefully acknowledged. S.G.W. and J.X. were supported by the National Basic Research Program of China (973 Program) under Contract No. 2007CB613906.